What term describes the ability of an atom to attract electrons?

The term that describes the ability of an atom to attract electrons is electronegativity. This concept is fundamental in understanding how atoms interact in chemical bonding. Electronegativity is a measure of an atom's tendency to attract and bond with electrons in a covalent bond. Higher electronegativity values indicate a stronger ability to attract electrons when forming bonds with other atoms, while lower values suggest a weaker attraction.

In the context of the other options: ionic radius refers to the size of an ion in a crystal lattice, which does not directly relate to an atom's ability to attract electrons. Ionization energy is the energy required to remove an electron from an atom, which pertains more to how easily an atom can lose electrons rather than gain them. Electron affinity measures the energy change when an electron is added to a neutral atom, which is related but focuses specifically on the energy aspect rather than the attraction itself. Thus, electronegativity is the most appropriate term for an atom's ability to attract electrons.